Change the "help" info to emphasize that this option refers
specifically to packaging the toolchain that would be built anyway.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42912 3c298f89-4303-0410-b956-a3cf2f4a3e73